Technical Field
The invention provides keyboard systems that auto-correct “sloppy” text entry due to errors in touching a keyboard or screen. More specifically, the invention provides a reduced keyboard such as those implemented on a touch-sensitive panel or display screen and to mechanical keyboard systems, using word-level analysis to resolve inaccuracies (sloppy text entry) in user entries. This invention is in the field of keypad input preferably for small electronic devices. Further, the invention relates to a directional input system with automatic correction.
Description of Background Art
For many years, portable computers have been getting smaller and smaller. The principal size-limiting component in the effort to produce a smaller portable computer has been the keyboard. If standard typewriter-size keys are used, the portable computer must be at least as large as the keyboard. Miniature keyboards have been used on portable computers, but the miniature keyboard keys have been found to be too small to be easily or quickly manipulated with sufficient accuracy by a user.
Incorporating a full-size keyboard in a portable computer also hinders true portable use of the computer. Most portable computers cannot be operated without placing the computer on a flat work surface to allow the user to type with both hands. A user cannot easily use a portable computer while standing or moving. In the latest generation of small portable computers, called Personal Digital Assistants (PDAs), companies have attempted to address this problem by incorporating handwriting recognition software in the PDA. A user may directly enter text by writing on a touch-sensitive panel or display screen. This handwritten text is then converted into digital data by the recognition software. Unfortunately, in addition to the fact that printing or writing with a pen is in general slower than typing, the accuracy and speed of the handwriting recognition software has to date been less than satisfactory. To make matters worse, today's handheld computing devices which require text input are becoming smaller still. Recent advances in two-way paging, cellular telephones, and other portable wireless technologies has led to a demand for small and portable two-way messaging systems, and especially for systems which can both send and receive electronic mail (“e-mail”).
It would therefore be advantageous to develop a much smaller keyboard for entry of text into a computer. As the size of the keyboard is reduced, the user encounters greater difficulty selecting the character of interest. In general there are two different types of keyboards utilized in such portable devices. One is the familiar mechanical keyboard consisting of a set of mechanical keys that are activated by depressing them with a finger or thumb. However, these mechanical keyboards tend to be significantly smaller than the standard sized keyboards associated with typewriters, desktop computers, and even “laptop” computers. As a result of the smaller physical size of the keyboard, each key is smaller and in closer proximity to neighboring keys.
This increases the likelihood that the user will depress an unintended key, and the likelihood of keystroke errors tends to increase the faster the user attempts to type.
Another commonly used type of keyboard consists of a touch-sensitive panel on which some type of keyboard overlay has been printed, or a touch-sensitive display screen on which a keyboard overlay can be displayed. Depending on the size and nature of the specific keyboard, either a finger or a stylus can be used to contact the panel or display screen within the area associated with the key that the user intends to activate. Due to the reduced size of many portable devices, a stylus is often used in order to attain sufficient accuracy in contacting the keyboard to activate each intended key. Here again, the small overall size of such keyboards results in a small area being associated with each key so that it becomes quite difficult for the average user to type quickly with sufficient accuracy.
One area of prior development in mechanical keyboards has considered the use of keys that are much smaller than those found on common keyboards. With smaller keys, the user must take great care in controlling each key press. One approach (U.S. Pat. No. 5,612,690) proposes a system that uses up to four miniature keys in unison to define primary characters (the alphabet) and nests secondary character rows (like numbers) between primary character rows. Selecting a secondary character involves depressing the miniature key from each of the surrounding primary characters. Grouping the smaller keys in this fashion creates a larger apparent virtual key composed of four adjacent smaller keys, such that the virtual key is large enough to be depressed using a finger. However, the finger must contact the keys more or less precisely on the “cross-hairs” of the boundaries between the four adjacent keys in order to depress them in unison. This makes it still difficult to type quickly with sufficient accuracy.
Another area of prior development in both touch screen and mechanical keyboards has considered the use of a much smaller quantity of full-size keys. With fewer keys, each single key press must be associated with a plurality of letters, such that each key activation is ambiguous as to which letter is intended. As suggested by the keypad layout of a touch-tone telephone, many of the reduced keyboards have used a 3-by-4 array of keys, where each key is associated with three or four characters (U.S. Pat. No. 5,818,437). Several approaches have been suggested for resolving the ambiguity of a keystroke sequence on such a keyboard. While this approach has merit for such keyboards with a limited number of keys, it is not applicable to reduced size keyboards with a full complement of keys.
Another approach in touch screen keyboards has considered analyzing the immediately preceding few characters in order to determine which character should be generated for a keystroke that is not close to the center of the display location of a particular character (U.S. Pat. No. 5,748,512). When the keyboard is displayed on a small touch screen, keystrokes that are off-center from a character are detected. Software compares the possible text strings of probable sequences of two or three typed characters against known combinations, such as a history of previously typed text or a lexicon of text strings rated for their frequency within a context. When the character generated by the system is not the character intended by the user, the user must correct the character before going on to select the a following character, because the generated character will be used to determine probabilities for the following keystroke.
The fundamental problem is that the specific activations that result from a user's attempts to activate the keys of a keyboard do not always precisely conform to the intentions of the user. On a touch screen keyboard, the user's finger or stylus may hit the wrong character or hit between keys in a boundary area not associated with a specific character. With a miniaturized mechanical keyboard, a given keypress may activate the wrong key, or may activate two or more keys either simultaneously or with a “roll-over” motion that activates adjacent keys in a rapid sequence. Other examples include common keyboards operated by users with limited ranges of motion or motor control, where there is a limited ability to consistently strike any particular space or key, or where the limb (such as in the case of an amputee, or the use of gloved hands or gloved fingers) or the device used to make the entry (such as a stylus) is far larger than the targeted key or character space.
Further, to operate a computing device, such as a computer, one or more input devices must be connected thereto. Since the early days of the computing age, the keyboard has been the primary input device for users to input textual messages into to computing devices. The textual messages may be commands for the computers to execute, or just plain data entry if he's using a keyboard as an input device. However, the user must memorize the correct spelling and syntax of computer commands. Even if the user has memorized the correct spelling, the input of data with keyboard itself can be error prone. Hence, a graphical user interface (GUI) has been developed for computing devices to reduce the use of keyboard. In a GUI, the user operates an alternative input device, such as a mouse, trackball, or joystick, to move around a cursor or pointer on the display. Once the cursor is moved to the desired position, a button is pressed and released, and a corresponding computer command is thus executed. Although a GUI provides an alternative way to invoke computer commands, the keyboard continues to serve as the primary text entry input device for computing devices.
Nevertheless, there are situations such as in console video-game machines or hand held devices with a joystick or joystub, where a traditional keyboard is neither available nor convenient. Currently, the text entry method for these systems usually consists of scrolling through an alphabet or on-screen QWERTY keyboard. Another commonly adopted navigation means in video-game machines provides users with a pie menu, which is a circular menu that allows users choose items by dragging the pointing device in the direction of the menu item. To input a word, the user must select each letter by scrolling through an alphabet list, navigating through the pie menu, or locating it on the on-screen keyboard and click a selection button after each letter is located.
The above text entry method has numerous disadvantages. For example: the method is inefficient because the user has to spend time in locating the letter and confirming the letter; the method is inconvenient because it breaks the normal typing flow when inserting clicks between letter selections; and the method is ineffective because the user could easily mistake an adjacent letter for the limited size of the on-screen keyboard.
What is desired is an effective text entry input system using a directional input means such as a joystick or trackball device. It is further desired that the text entry input system is intuitive and easy to operate. It is still further desired that the text entry input system can provide auto-correction of input mistakes.